Portable device for the photographing of book pages

ABSTRACT

Two transparent plates constitute with each other an angle variable from about 60 to 120 degrees along their common edge. A book to photograph is opened at the chosen pages and placed sitting on said common edge. A photographic camera is attached near the free edge of one of the plates through a supporting element in such a way that the optical axis of the camera stays perpendicular to the one plate. A first planar mirror, which has one edge in common with the common edges of the transparent plates, is maintained exactly in the middle of the angle formed by the transparent plates but can be folded against the one plate. A second mirror which has one edge in common with the one plate near its free edge, is maintained perpendicular to the reference position of the first mirror.

FIELD OF THE INVENTION

[0001] The present invention concerns a portable device allowingphotographing of two adjacent pages anywhere in a book while opening thebook by an angle lower than 120 degrees.

BACKGROUND OF THE INVENTION

[0002] Optical devices designed to allow to photograph any page of abook while opening the book by an angle as small as possible have beenproposed before.

[0003] An example of such a device, allowing photographing of both pagesof a book at a time, is described for example in German Patent DE 35 46404. In this patent, a number of implementations of transparent platescombined with mirrors are described. In some implementations, the numberof mirrors used is as high as nine. The German Patent does not citeportability and ease of use as goals of the invention. There is also noindication on how to aim the camera at the center of book pages ofvariable sizes.

SUMMARY OF THE INVENTION

[0004] When compared to the present invention, the devices of the priorart lack:

[0005] portability, because of the number, size and locations of themirrors used in their various implementations and the absence of meansto reduce their bulk for transportability, and

[0006] simple means to adjust the position of the camera to aim itsoptical axis at the center of various size pages, particularly if theyhave to be used by blind individuals.

[0007] The operating principles of a device in conformity with thepresent invention are similar to the operating principles of the devicedescribed in French Patent Application serial number 01 16 172, filed onDec. 4, 2002. Although, while in the previous design, the book had to beturned over to photograph successively two opposite pages, in thepresent invention one only needs to fold a mirror against one of thetransparent plates carrying the book to switch between opposite pages.Another benefit of the new design is that the optical distance betweenthe page surface and the camera lens surface is practically constantwhen the camera is aimed at the center of pages of books of differentsizes.

[0008] These and other objects of the invention, as well as many of theintended advantages thereof, will become more readily apparent whenreference is made to the following description taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a schematic illustration of a positioning of twotransparent plates and two mirrors for photographing two pages of abook.

[0010]FIG. 2 is a schematic illustration of an alternate positioning oftwo of the transparent plates and one of the mirrors.

[0011]FIG. 3 shows the plates and mirrors folded for transport.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention concerns a portable device allowingphotographing of any page of a book while opening the book by an anglefrom about 60 to 120 degrees, therefore without damaging it. The deviceis designed in such a way that it can be used by blind people withoutexternal help, in order to become the first part of a portable bookreading machine.

[0013] A preferred embodiment of a device in conformity with the presentinvention is shown in FIGS. 1 to 3. Dimensions of the objectsrepresented parallel to the plane of the drawing will be called lengthsor widths, dimensions perpendicular to the plane of the drawing will becalled heights.

[0014] Two transparent plates PT1 and PT2, both perpendicular to theplane of the drawing, are held together by two hinges CH1 attached tothe front and the rear of their top edges, in such a way that the middlesection of said edges is left free to hold an opened book sitting ontheir top between the hinges. Said plates can rotate with respect toeach other along the common axis of said hinges.

[0015] Four short cylindrical front and rear rods AB1 and AB2, alsoperpendicular to the plane of the drawing are respectively attached tothe front and rear edges of the plates PT1 and PT2 in such a way thatthe plane defined by the axis of the rods AB1 and the axis of the hingesCH1 is parallel to the plate PT1 and the plane defined by the axis ofthe rods AB2 and the axis of the hinges CH1 is parallel to the platePT2. The axis of the rods AB1 and AB2 are at the same distance from theaxis of the hinges CH1.

[0016] Two levers BL1 are attached at one end to the front and rear rodsAB1 in such a way that they can rotate around the common axis of saidrods, and two identical levers BL2 are attached at one end to the frontand rear rods AB2 in such a way that they can rotate around the commonaxis of said rods. The free ends of the levers BL1 and BL2 are attachedto a rod ABC perpendicular to the plane of the drawing in such a waythat they can rotate around the axis of the rod ABC.

[0017] The axis of the rods AB1 and AB2 are at the same distance fromthe axis of the rod ABC, this distance being equal to the distancebetween the axis of the rods AB1 or AB2 from the axis of the hinges CH1.

[0018] The axis of the rod ABC is therefore maintained exactly in themiddle of the angle between the plates PT1 and PT2 when this anglevaries. During this motion, the axis of the rod ABC stays on a cylinderC which has the same axis as the rod AB2. The plates PT1 and PT2 beingof the same length, when they stand along their bottom free edge on anhorizontal plane surface, the plane defined by the axis of the rod ABCand the axis of the hinges CH1 stays vertical when the angle between theplates PT1 and PT2 varies.

[0019] The rod ABC comprises three cylindrical sections: two sections ofthe same diameter as the rods AB1 and AB2 at each end and a middlesection of a larger diameter and of the same height as the transparentplates PT1 and PT2.

[0020] A planar rectangular mirror mV, extending perpendicular to theplane of the drawing, and of the same height as the plates PT1 and PT2,is attached by its upper edge at the axis of the hinges CH1 in such away that it can freely rotate around said axis and can be folded againstthe plate PT2. When the plates PT1 and PT2 stand along their bottom freeedge on an horizontal plane surface, the mirror mV hangs naturally in avertical position halfway between said plates. In order to allow themirror mV to occupy this position, a flat area has been cut in thecentral section of the rod ABC at a distance from the rod axis equal tohalf the thickness of the mirror mV, allowing said mirror to rotatefreely between its vertical position against the rod ABC and its foldedposition against the plate PT2.

[0021] Two identical extension plates EmV extending parallel to theplane of the drawing are attached to the front and rear bottom edges ofthe mirror mV in such a way that the mirror mV stays in the planedefined by the axis of the rod ABC and the axis of the hinges CH1, whensaid extension plates are sitting against the rod ABC on its side facingthe plate PT2. Thanks to said extensions, the mirror mV is maintained inthe middle of the angle defined by the plates PT1 and PT2, even if saidmirror is too short to reach the rod ABC when said angle is decreasedand therefore the distance between the axis of the rod ABC and the axisof the hinges CH1 increases.

[0022] A plane rectangular mirror mH, extending perpendicular to theplane of the drawing, and of the same height as the mirror mV and theplates PT1 and PT2, is attached by its right edge to the plate PT2 nearthe lower edge of said plate by two hinges CH2 attached to the front andrear angles of the plate PT2 and of the mirror mH, in such a way thatthe plane defined by the common axis of the hinges CH2 and the commonaxis of the hinges CH1 is parallel to the surface of the plate PT2 andcontains the axis of the rods AB2. The distance between the axis of thehinges CH2 and the axis of the rods AB2 is chosen to be equal to thedistance between the axis of the hinges CH1 and the axis of the rodsAB2. Therefore, the plane defined by the axis of the rod ABC and theaxis of the hinges CH2 remains perpendicular to the plane defined by theaxis of the rod ABC and the axis of the hinges CH1 when the anglebetween the plates PT1 and PT2 varies.

[0023] The mirror mH is kept parallel to the plane defined by the axisof the rod ABC and the axis of the hinges CH2 by means of two extensionplates EmH extending parallel to the plane of the drawing, attached tothe front and rear edges of the mirror mH near its free left edge, whensaid extension plates are resting on top of the end sections of the rodABC.

[0024] Thanks to said extensions, the mirror mH is maintainedperpendicular to the mirror mV, the mirror mH being by design too shortto reach the rod ABC, in order to prevent the lower edge of the mirrormV from bumping into the left edge of the mirror mH when the mirror mVis rotated to be folded against the plate PT2.

[0025] A photographic camera CA is attached to the transparent plate PT2by means of a support SCA in such a way that the optical axis of thecamera is perpendicular to the plate PT2 halfway between the front andthe rear of said plate and cuts the external surface of said plate at apoint O. The camera lens can protrude through and below the insidesurface of the plate PT2 through a circular hole cut in said plate.

[0026] When the mirror mV is in its vertical reference position, a lightray coming from the point O along the camera optical axis will reach,after successive reflections on the mirror mH and the mirror mV, a pointP2 on the external surface of the plate PT2 located symmetrically fromthe point O with respect to the projection H of the intersection of thereflecting surface of mirrors mH and mV on the external surface of theplate PT2. The point H and therefore the point P2 aimed at by the cameramove closer to the inside border of the page of a book sitting on theplates PT1 and PT2 when the angle between said plates increases, andmoves towards its outside border when said angle decreases, thusallowing the camera to be aimed at the center of various size bookssimply by varying said angle.

[0027] When the mirror mV is folded against the plate PT2, a light raycoming from the point O along the camera optical axis will reach, aftera single reflection on the mirror mH a point P1 located on the externalsurface of the plate PT1 symmetrically from the point P2 with respect tothe plane defined by the axis of the rod ABC and the axis of the hingesCH1, which is a plane of symmetry for the plates PT1 and PT2. If onecalls OI the image of the point produced by the mirror mH, a light raycoming from the point O along the camera optical axis will follow theline OI-P1 after a single reflection on the mirror mH.

[0028] When an opened book is placed sitting on the top of the platesPT1 and PT2, one can photograph its right page when the mirror mV ishanging freely in its vertical position, or its left page when themirror mV is temporarily kept folded against the plate PT2.

[0029] The minimal length, in the drawing plane, of the mirrors mV andmH is defined by the widest page to be photographed and the maximumoptical opening of the camera lens. If one calls CP the intersection ofthe top edge of the circle representing the opening pupil of the lenswith a plane parallel to the plane of the drawing containing the centerO of this pupil, and one calls OPI the image of CP produced by themirror mH, and one calls OP1 the intersection of the external border ofthe page sitting against the plate PT1 with said plane, the intersectionof the line OP1-OPI with the mirrors mV and mH defines their minimallength. The corresponding opening angle of the book is shown on FIG. 1.

[0030] The maximum value of the angle defined by the plates PT1 and PT2,and therefore the smallest page at which center the camera can be aimed,is defined by the need to be able to fold the mirror mV against theplate PT2 without having its lower edge bumping against the left edge ofthe mirror mH. The corresponding opening angle of the book is shown onFIG. 2.

[0031] The constraints cited above explain the need for the extensionplates EmH and EmV to keep the mirrors mV and mH in their referencepositions perpendicular to each other, both for the smallest and thelargest angle between the plates PT1 and PT1, corresponding respectivelyto the smallest and the largest book page width which can be centered inthe camera field of view.

[0032] In the embodiment of the invention shown in FIGS. 1 to 3, thehorizontal extension plates EmH carry on their bottom edge three slotsEN defining three fixed values of the opening angle of the bookcorresponding to three fixed values of their page width, easy toretrieve for example by a blind user.

[0033] If a continuous adjustment of said angle is desired, theextension plates EmH will carry longer slots defining only the minimumand maximum values of said angle and intermediate positions will be keptby tightening against the extension plates two screws fitted on thethreaded end sections of the rod ABC.

[0034] If an electrically controlled adjustment of said angle isdesired, the extension plates EmH will carry on their lower edge asingle long rack each, defining only the minimum and maximum values ofsaid angle and intermediate positions being kept by gears driven by twostepping motors attached to the end sections of said rod.

[0035] If the camera used is a digital camera providing a video outputrepresenting the content of the image in the camera field of view, thisvideo output can be analyzed to detect the position of the page borderswith respect to the camera field of view, therefore providing theinformation needed to adjust by means of electrical signals andautomatically, both the centering of the camera optical axis on the pageand the camera focal length (zoom) to match the page size and the camerafield of view.

[0036] To fold down the device in its transport position, one followsthese steps:

[0037] remove the camera from its position on the plate PT2,

[0038] fold the mirror mV against the plate PT2,

[0039] fold the mirror mH against the mirror mV and the plate PT2 bylifting up the extension plates EmH,

[0040] fold the plate PT1 as close as possible to the mirror mH, themirror mV and the plate PT2, by flattening the top and bottom angles ofthe lozenge constituted by the transparent plates and the levers BL1 andBL2.

[0041]FIG. 3 shows the device completely folded for easy transport.

[0042] In summary, two transparent plates PT1 and PT2 constitute witheach other an angle variable from about 60 to 120 degrees along theircommon edge. The book to photograph is opened at the chosen pages andplaced sitting on said common edge. A photographic camera CA is attachednear the free edge of the plate PT2 through a supporting element SCA insuch a way that the optical axis of the camera stays perpendicular tothe plate PT2.

[0043] A planar mirror mV, which has one edge in common with the commonedges of the transparent plates, is maintained exactly in the middle ofthe angle formed by the transparent plates but can be folded against theplate PT2. A mirror mH which has one edge in common with the plate PT2near its free edge, is maintained perpendicular to the referenceposition of the mirror mV.

[0044] By successive reflections on the mirrors mH, then mV, the opticalaxis of the camera aims at the page of the book maintained against theplate PT2 when the mirror mV is in its reference position, and byreflection only on the mirror mH it aims at the opposite page of thebook maintained against the plate PT1, when the mirror mV is held foldedagainst the plate PT2. The points at which the optical axis of thecamera are aimed at, move closer to the inside border of the pages whenthe angle between the plates PT1 and PT2 increases, and move closer totheir outside border when this angle decreases.

[0045] The transparent plates and mirrors are held in their operatingpositions by two sets of levers BL1 and BL2 pressed against the lateraledges of the plates and constitute together with the plates twodeformable lozenges. The mirrors and the angle between the plates PT1and PT2 are maintained by means of two extension levers EmV and EmHresting on a rod ABC which constitutes one summit of the lozenges.Hinges attached on the common edges of the groups of plates PT1-mV-PT2and mH-PT2 allow both the variation of the angle between the transparentplates and folding the whole device for easy transport.

[0046] The foregoing description should be considered as illustrativeonly of the principles of the invention. Since numerous modificationsand changes will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described, and, accordingly, all suitable modifications andequivalents may be resorted to, falling within the scope of theinvention.

We claim:
 1. A device to photograph two adjacent pages of a book, saiddevice comprising: two transparent plates having a common edge toconstitute together an angle comprised between about 60 and 120 degrees,means to maintain said plates in their respective positions, means tohold the book sitting on top of said plates, two adjacent pages beingapplied against an external surface of said plates, a first mirrorhaving an edge in common with the common edge of said transparentplates, in such a way that the first mirror can be positioned in one ofa middle of the angle defined by said plates and folded against one ofsaid plates, a second mirror having an edge close to a free edge of oneof said transparent plates near the free edge, in order to constitutetogether an angle comprised between about 60 and 30 degrees, means tomaintain said second mirror perpendicular to said first mirror, andmeans to position a photographic camera near the edge of the transparentplate close to said second mirror in such a way that an optical axis ofthe camera is perpendicular to the transparent plate which carries thecamera and can be aimed by successive reflections on said mirrors at thepage of a book placed against the transparent plate holding the camera,and by reflection only on said second mirror at the page of the bookplaced against the other transparent plate.
 2. Device according to claim1, wherein said transparent plates rotate around an axis near andparallel to the common edge in such a way that a point of the book pageat which the camera is aimed moves towards an inside border of the pagewhen the angle defined by said transparent plates increases, and towardsan external border of the page when said angle decreases, allowing saidpoint to be placed at the center of the page of books of various sizes.3. Device according to claim 1, wherein the means used to position saidmirrors comprise a rod whose axis is kept in a plane of symmetry of theangle defined by said transparent plates, said mirrors being able torest on said rod while remaining perpendicular to each other with one ofsaid mirrors occupying a position parallel and near to said plane ofsymmetry.
 4. Device according to claim 3, wherein the means used toposition said rod comprise four levers of same length arranged in twogroups of two levers each respectively placed against the front and rearedges of said transparent plates in such a way that the leversconstitute with said plates two identical lozenges, one in the front,the other in the rear of said plates, said lozenges being held togetherby said rod in such a way that said levers rotate: on one hand aroundthe axis of said rod at one summit of said lozenges, on the other handaround the common axis of two short rods attached to the front and rearedges of both transparent plates, constituting two other summits of saidlozenges, thus allowing an aperture angle of said lozenges to varyaccording to a value of the angle formed by said transparent plates at afourth summit of said lozenges.
 5. Device according to claim 4, whereinthe means used to keep said mirrors perpendicular to each other and tokeep one of the mirrors parallel to the plane of symmetry of saidtransparent plates, comprise two extension plates for each said mirror,said extension plates being attached to said mirrors at the front andrear angles near their free edge, in such a way that: when saidextension plates rest against a rod which constitutes a bottom summit ofsaid lozenges, the extension plates maintain said mirrors in theirreference positions, when the extension plates belonging to the mirrorperpendicular to the plane of symmetry of said transparent plates arelifted up and away from said rod, said mirror is folded against thetransparent plate holding said camera.
 6. Device according to claim 5,wherein the extension plates belonging to the mirror perpendicular tothe plane of symmetry of said transparent plates carry on a lower edgeseveral slots each, inside which end sections of said rod are positionedto maintain the angle formed by said transparent plates at one ofseveral values, according to a width of the pages to be photographed. 7.Device according to claim 1, wherein the camera used is a digital cameraproviding a video output representing content of an image in a camerafield of view, the video output is analyzed to detect a position of thepage borders with respect to the camera field of view, providinginformation needed to adjust both centering of the camera optical axison the page and the camera focal length to match the page size and thecamera field of view.